<?php
/**
 *  
 * @package package_name
 * @author Mervin.Wong<mervin0502@163.com>
 * @copyright
 * @license  http://www.apache.org/licenses/LICENSE-2.0
 * @version 0.1.0
 * @date 2013-3-2下午9:31:32
 *
 */
 
 /**
  * CanGoo common helper
  * 公共函数
  * @package blog
  * @subpackage helper
  * @category helper
  * @author mervin.wong
  * @link url description
  */
 
/**
 +----------------------------------------------------------
 * 字符串截取，支持中文和其他编码
 +----------------------------------------------------------
 * @param string $source 需要转换的字符串
 * @param string $start 开始位置
 * @param string $length 截取长度
 * @param string $charset 编码格式
 * @param string $suffix 截断显示字符后缀
 +----------------------------------------------------------
 * @return string
 +----------------------------------------------------------
 */
 if(!function_exists('cut_str')){

	function cut_str($source, $start=0, $length, $charset="utf-8", $suffix=""){
	    if(function_exists("mb_substr"))        //采用PHP自带的mb_substr截取字符串
	    {
	        $string = mb_substr($source, $start, $length, $charset).$suffix;
	    }
	    elseif(function_exists('iconv_substr')) //采用PHP自带的iconv_substr截取字符串
	    {
	        $string = iconv_substr($source,$start,$length,$charset).$suffix;
	    }
	    else
	    {
	        $pattern['utf-8']   = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";
	        $pattern['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";
	        $pattern['gbk']    = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";
	        $pattern['big5']   = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";
	        preg_match_all($pattern[$charset], $source, $match);
	        $slice = join("",array_slice($match[0], $start, $length));
	        
	        $string = $slice.$suffix;
	    }
	    return $string;
	}
 }